ABSTRACT This supplement request is for a Phase 3, randomized, stratified, observer-blind, placebo- controlled study to evaluate the efficacy, safety and immunogenicity, of mRNA-1273 vaccine compared to placebo in adults 18 years of age and older who have no known history of SARS- CoV-2 infection but whose locations or circumstances put them at appreciable risk of acquiring COVID-19 and/or SARS-CoV-2 infection. This request also relates to other COVID 19 activities.